Tindak Balas Di Antara Beta-Karotena Dalam Minyak Kelapa Sawit Dengan Asid Dan Dengan Ion Ferik
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Date
1995-06
Authors
Goh, Leong San
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Abstract
The reaction between H+ or Fe 3+ with carotenes
in palm oil produced a blue green solution. Analysis
using the uv-spectrometer and electric conductivity
indicated that the blue green colouration was ionic in
nature. The absorption peaks in the uv-vis-spectrum
were related to the cations formed from carotene .The
cations formed in the reaction of carotenes in palnl oil
with acid absorbed at an absorption maximum of 899 nm
i ni tially. Location of thisĀ· peak then shifted to 675
nm .Cations were also formed in the reaction of H+ or
Fe3+ with pure carotenes. Peak appeared initially at
920 nm then shifted to 715 nm finally for the reaction
of beta-carotenes with acid. The reaction between Fe3+
with beta-carotenes gave a peak at 924 nm and then
shifted to 720 nm. The observed shifts in the absorption
maximum from -900 nm to 700 nm implied that there
was a change in the conjugation of the double bonds in
the carotene cations. These cations could also be obtained
through the reactions of beta-carotene with
trichloroacetic acid." The conductivity of the carotene
solution increased initially and achieved an equalibrium
value finally. The cations formed could be destroyed
by adding water. A riumber of products were obtained by
silica column separation. The eluted fraction absorbed
at ... 400 nm. The identi.ty of the major fraction retained
on the top of the column was found ~o be oligomers
with 2-3 units of carotene molecules. Kinetic
studies on the reaction between beta-carotenes and
sulfuric acid showed that two,stages were involved. The
first stage was pseudo first order whi le the second
stage was first order in carotene. The activation
energy for the first stage of the reaction was 65.2
KJ/mol ; and 9.5 KJ/mol for the second stage reaction.
Reaction between F'e3+ and beta-carotene solution
yielded a black solid at high concentration. Kinetics
of the reaction of Fe3+ with carotene solution was
first order. The overall reaction scheme was proposed.
Description
Keywords
The blue green colouration , was ionic in nature